<?php

/**
 * CakeEventManager Extensible.
 *
 * PHP versions 5
 * CAKEPHP versions 2.x
 * 
 * Green CMS - Content Management System and Framework Powerfull by Cakephp
 * Copyright 2012, GREEN GLOBAL CO., LTD (toancauxanh.vn)
 * 
 * CakePHP(tm) :  Rapid Development Framework (http://www.cakephp.org)
 * Copyright 2005-2011, Cake Software Foundation, Inc. (http://www.cakefoundation.org)
 *
 * Licensed under The MIT License
 * Redistributions of files must retain the above copyright notice.
 *
 * @author        Technology Lab No.I <tech1@toancauxanh.vn>
 * @link          
 * @package       Green.Event
 * @since         Green v 1.0
 * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
 */
App::uses('CakeEventListener', 'Event');

/**
 * The event manager is responsible for keeping track of event listeners and pass the correct
 * data to them, and fire them in the correct order, when associated events are triggered. You
 * can create multiple instances of this objects to manage local events or keep a single instance
 * and pass it around to manage all events in your app.
 *
 * @package Cake.Event
 */
class CakeEventManager {

    /**
     * The default priority queue value for new attached listeners
     *
     * @var int
     */
    public static $defaultPriority = 10;

    /**
     * The default pass params value for new attached listeners
     *
     * @var boolean
     */
    public $defaultPassParams = false;

    /**
     * The globally available instance, used for dispatching events attached from any scope
     *
     * @var CakeEventManager
     */
    protected static $_generalManager = null;

    /**
     * List of listener callbacks associated to
     *
     * @var object $Listeners
     */
    protected $_listeners = array();

    /**
     * Internal flag to distinguish a common manager from the sigleton 
     *
     * @var boolean
     */
    protected $_isGlobal = false;

    /**
     * Returns the globally available instance of a CakeEventManager
     * this is used for dispatching events attached from outside the scope
     * other managers were created. Usually for creating hook systems or inter-class
     * communication
     *
     * If called with a first params, it will be set as the globally available instance
     *
     * @param CakeEventManager $manager 
     * @return CakeEventManager the global event manager
     */
    public static function instance($manager = null) {
        if ($manager instanceof CakeEventManager) {
            self::$_generalManager = $manager;
        }
        if (empty(self::$_generalManager)) {
            self::$_generalManager = new CakeEventManager;
        }

        self::$_generalManager->_isGlobal = true;
        return self::$_generalManager;
    }

    /**
     * Adds a new listener to an event. Listeners 
     *
     * @param callback|CakeEventListener $callable PHP valid callback type or instance of CakeEventListener to be called
     * when the event named with $eventKey is triggered. If a CakeEventListener instances is passed, then the `implementedEvents`
     * method will be called on the object to register the declared events individually as methods to be managed by this class.
     * It is possible to define multiple event handlers per event name.
     *
     * @param mixed $eventKey The event unique identifier name to with the callback will be associated. If $callable
     * is an instance of CakeEventListener this argument will be ignored
     *
     * @param array $options used to set the `priority` and `passParams` flags to the listener.
     * Priorities are handled like queues, and multiple attachments into the same priority queue will be treated in
     * the order of insertion. `passParams` means that the event data property will be converted to function arguments
     * when the listener is called. If $called is an instance of CakeEventListener, this parameter will be ignored
     *
     * @return void
     * @throws InvalidArgumentException When event key is missing or callable is not an
     *   instance of CakeEventListener.
     */
    public function attach($callable, $eventKey = null, $options = array()) {
        if (!$eventKey && !($callable instanceof CakeEventListener)) {
            throw new InvalidArgumentException(__d('cake_dev', 'The eventKey variable is required'));
        }
        if ($callable instanceof CakeEventListener) {
            $this->_attachSubscriber($callable);
            return;
        }
        $options = $options + array('priority' => self::$defaultPriority, 'passParams' => $this->defaultPassParams);
        $this->_listeners[$eventKey][$options['priority']][] = array(
            'callable' => $callable,
            'passParams' => $options['passParams'],
        );
    }

    /**
     * Auxiliary function to attach all implemented callbacks of a CakeEventListener class instance
     * as individual methods on this manager
     *
     * @param CakeEventListener $subscriber
     * @return void
     */
    protected function _attachSubscriber(CakeEventListener $subscriber) {
        foreach ($subscriber->implementedEvents() as $eventKey => $function) {
            $options = array();
            $method = $function;
            if (is_array($function) && isset($function['callable'])) {
                list($method, $options) = $this->_extractCallable($function, $subscriber);
            } elseif (is_array($function) && is_numeric(key($function))) {
                foreach ($function as $f) {
                    list($method, $options) = $this->_extractCallable($f, $subscriber);
                    $this->attach($method, $eventKey, $options);
                }
                continue;
            }
            if (is_string($method)) {
                $method = array($subscriber, $function);
            }
            $this->attach($method, $eventKey, $options);
        }
    }

    /**
     * Auxiliary function to extract and return a PHP callback type out of the callable definition
     * from the return value of the `implementedEvents` method on a CakeEventListener
     *
     * @param array $function the array taken from a handler definition for a event
     * @param CakeEventListener $object The handler object
     * @return callback
     */
    protected function _extractCallable($function, $object) {
        $method = $function['callable'];
        $options = $function;
        unset($options['callable']);
        if (is_string($method)) {
            $method = array($object, $method);
        }
        return array($method, $options);
    }

    /**
     * Removes a listener from the active listeners.
     *
     * @param callback|CakeEventListener $callable any valid PHP callback type or an instance of CakeEventListener
     * @return void
     */
    public function detach($callable, $eventKey = null) {
        if ($callable instanceof CakeEventListener) {
            return $this->_detachSubscriber($callable, $eventKey);
        }
        if (empty($eventKey)) {
            foreach (array_keys($this->_listeners) as $eventKey) {
                $this->detach($callable, $eventKey);
            }
            return;
        }
        if (empty($this->_listeners[$eventKey])) {
            return;
        }
        foreach ($this->_listeners[$eventKey] as $priority => $callables) {
            foreach ($callables as $k => $callback) {
                if ($callback['callable'] === $callable) {
                    unset($this->_listeners[$eventKey][$priority][$k]);
                    break;
                }
            }
        }
    }

    /**
     * Auxiliary function to help detach all listeners provided by an object implementing CakeEventListener
     *
     * @param CakeEventListener $subscriber the subscriber to be detached
     * @param string $eventKey optional event key name to unsubscribe the listener from
     * @return void
     */
    protected function _detachSubscriber(CakeEventListener $subscriber, $eventKey = null) {
        $events = $subscriber->implementedEvents();
        if (!empty($eventKey) && empty($events[$eventKey])) {
            return;
        } elseif (!empty($eventKey)) {
            $events = array($eventKey => $events[$eventKey]);
        }
        foreach ($events as $key => $function) {
            if (is_array($function)) {
                if (is_numeric(key($function))) {
                    foreach ($function as $handler) {
                        $handler = isset($handler['callable']) ? $handler['callable'] : $handler;
                        $this->detach(array($subscriber, $handler), $key);
                    }
                    continue;
                }
                $function = $function['callable'];
            }
            $this->detach(array($subscriber, $function), $key);
        }
    }

    /**
     * Dispatches a new event to all configured listeners
     *
     * @param mixed $event the event key name or instance of CakeEvent
     * @return void
     */
    public function dispatch($event) {
        if (is_string($event)) {
            $event = new CakeEvent($event);
        }

        if (!$this->_isGlobal) {
            self::instance()->dispatch($event);
        }

        if (empty($this->_listeners[$event->name()])) {
            return;
        }

        foreach ($this->listeners($event->name()) as $listener) {
            if ($event->isStopped()) {
                break;
            }
            if ($listener['passParams'] === true) {
                $result = call_user_func_array($listener['callable'], $event->data);
            } else {
                $result = call_user_func($listener['callable'], $event);
            }
            if ($result === false) {
                $event->stopPropagation();
            }
            if ($result !== null) {
                $event->result = $result;
            }
            continue;
        }
    }

    /**
     * Returns a list of all listeners for a eventKey in the order they should be called
     *
     * @param string $eventKey
     * @return array
     */
    public function listeners($eventKey) {
        if (empty($this->_listeners[$eventKey])) {
            return array();
        }
        ksort($this->_listeners[$eventKey]);
        $result = array();
        foreach ($this->_listeners[$eventKey] as $priorityQ) {
            $result = array_merge($result, $priorityQ);
        }
        return $result;
    }

}